Filter insert

Abstract

A filter insert, which combines high mechanical load-bearing capacity with good characteristics as regards the shedding of filter cake, has lateral filter walls which are folded in planar or zigzag manner and which are connected to horizontal wall components in mechanically loadable and air-tight manner. The unit so obtained is in turn connected in tight and mechanically loadable manner to a top section by which the filter insert is capable of being attached to the perforated plate of a filter casing.

What is claimed is: 
     
       1. A back-flushable filter insert, comprising: (a) a top section having means for attaching to a perforated plate of a filter casing;   (b) a pocket-shaped filter section fixed tightly against the top section, the filter section comprising (i) two lateral filter walls each folded in a zig-zag manner, (ii) an upper inherently rigid wall component, (iii) a lower inherently rigid wall component, and (iv) a rear inherently rigid wall component, wherein the filter walls and the wall components are connected to one another and to the top section in a fluid-tight and mechanically loadable structure to maintain a high degree of mechanical stability, both during application of a relatively low pressure to the filter insert during filtration and also during application of a relatively higher pressure to the filter insert during backflushing, and   at least one central internal component supporting the filter walls and positioned between the upper inherently rigid wall component and the lower inherently rigid wall component.   
     
     
       2. A filter insert as claimed in claim 1, wherein: the inherently rigid wall components each comprise at least one of either an injection-molded material or a cast material.   
     
     
       3. A filter insert as claimed in claim 2, wherein: the wall components comprise a synthetic material.   
     
     
       4. A filter insert as claimed in claim 2, wherein: the wall components are injection moulded or cast onto the filter walls.   
     
     
       5. A filter insert as claimed in claim 1, wherein: the central internal component is arranged to be substantially parallel to the lower wall component.   
     
     
       6. A filter insert as claimed in claim 1, wherein: the internal component is made integral with the wall components.   
     
     
       7. A filter insert as claimed in claim 1, wherein: at least some of the rigid wall components have edge faces whose configurations match the configurations of corresponding filter walls to which said edge faces respectively abut.   
     
     
       8. A filter insert as claimed in claim 7 wherein: the filter walls each have a zigzag configuration, and the configurations of some of the edge faces of the wall components which respectively engage with the filter walls are such as to enable engagement with the zigzag edges of the filter walls.   
     
     
       9. A filter insert as claimed in claim 7, wherein: the edge faces of said at least some wall components are attached to the filter walls by one of bonding, welding or casting in place.   
     
     
       10. A filter insert as claimed in claim 1, wherein: an aperture is formed in the top section, the aperture leading to the interior of the filter section and being tapered outwardly with increasing distance from the filter section.   
     
     
       11. A filter insert as claimed in claim 10, wherein: the aperture has substantially planar divergent lateral wall surfaces.   
     
     
       12. A filter insert as claimed in claim 1, wherein: the rear wall component bears an engaging element formed to cooperate with a corresponding casing element to support the rear wall component.   
     
     
       13. A filter insert as claimed in claim 1, further including: circumferential sealing means provided on one of the end faces of the top section.